Nodular Fasciitis of the Posterior Chest Wall With Bone Invasion Mimicking a Malignant Neoplasm

Nodular fasciitis is a self-limiting benign fibroblastic/myofibroblastic proliferation, which typically presents as a rapidly growing mass resembling an aggressive lesion clinically. It can also mimic a sarcoma histologically, hence the frequent characterization as “pseudosarcoma.” We describe a case of a 53-year-old man who presented with a posterior chest wall mass that on imaging showed erosion into the adjacent ribs. After resection, the diagnosis of nodular fasciitis was rendered. Bone erosion by nodular fasciitis is extremely rare and can resemble a malignant neoplasm radiologically.